Control wafers may be used to monitor integrated circuit (IC) processes such as, for example, etch rates.
U.S. Pat. No. 5,086,017 to Lu describes a laser interferometry etch rate monitor methods in a silicide process.
U.S. Pat. No. 5,872,062 to Hsu describes a method for etching titanium nitride.
U.S. Pat. No. 5,547,881 to Wang et al. describes an APM etch process for metal nitrides and other layers.
U.S. Pat. No. 5,516,399 to Balconi-Lamica et al. describes etch rate monitor processes.